/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "stdosl.h"
#include "node_texture.h"

/* Gradient */

float gradient(point p, string type)
{
  float x, y, z;

  x = p[0];
  y = p[1];
  z = p[2];

  float result = 0.0;

  if (type == "linear") {
    result = x;
  }
  else if (type == "quadratic") {
    float r = max(x, 0.0);
    result = r * r;
  }
  else if (type == "easing") {
    float r = min(max(x, 0.0), 1.0);
    float t = r * r;

    result = (3.0 * t - 2.0 * t * r);
  }
  else if (type == "diagonal") {
    result = (x + y) * 0.5;
  }
  else if (type == "radial") {
    result = atan2(y, x) / M_2PI + 0.5;
  }
  else {
    float r = max(1.0 - sqrt(x * x + y * y + z * z), 0.0);

    if (type == "quadratic_sphere")
      result = r * r;
    else if (type == "spherical")
      result = r;
  }

  return result;
}

shader node_gradient_texture(
    int use_mapping = 0,
    matrix mapping = matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),
    string type = "linear",
    point Vector = P,
    output float Fac = 0.0,
    output color Color = 0.0)
{
  point p = Vector;

  if (use_mapping)
    p = transform(mapping, p);

  Fac = gradient(p, type);
  Color = color(Fac, Fac, Fac);
}
